U.S. patent application number 13/382282 was filed with the patent office on 2012-05-10 for lighting device for endoscope and endoscope device.
Invention is credited to Akira Mizuyoshi, Takaaki Saito.
Application Number | 20120116159 13/382282 |
Document ID | / |
Family ID | 43429225 |
Filed Date | 2012-05-10 |
United States Patent
Application |
20120116159 |
Kind Code |
A1 |
Mizuyoshi; Akira ; et
al. |
May 10, 2012 |
LIGHTING DEVICE FOR ENDOSCOPE AND ENDOSCOPE DEVICE
Abstract
A lighting device includes first and second light sources, a
wavelength converting member and a light quantity ratio changing
unit. A first light source uses a semiconductor light emitting
device as an emission source. A second light source uses, as an
emission source, a semiconductor light emitting device of a
different emission wavelength from the first light source. A
wavelength converting member is excited for light emission by light
emitted from at least one of the first light source and the second
light source. The light quantity ratio changing unit changing a
light quantity ratio between the light emitted from the first light
source and the light emitted from the second light source.
Inventors: |
Mizuyoshi; Akira; (Kanagawa,
JP) ; Saito; Takaaki; (Kanagawa, JP) |
Family ID: |
43429225 |
Appl. No.: |
13/382282 |
Filed: |
July 5, 2010 |
PCT Filed: |
July 5, 2010 |
PCT NO: |
PCT/JP2010/061432 |
371 Date: |
January 4, 2012 |
Current U.S.
Class: |
600/109 ;
362/84 |
Current CPC
Class: |
A61B 1/0638 20130101;
A61B 1/063 20130101; A61B 1/0653 20130101; A61B 5/0084 20130101;
A61B 1/0005 20130101; A61B 1/0684 20130101; A61B 1/07 20130101 |
Class at
Publication: |
600/109 ;
362/84 |
International
Class: |
A61B 1/04 20060101
A61B001/04; F21V 9/16 20060101 F21V009/16 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 6, 2009 |
JP |
2009-159962 |
Claims
1. A lighting device for an endoscope obtaining illumination light
by using light emitted from a plurality of light sources,
comprising: a first light source that uses a semiconductor light
emitting device as an emission source; a second light source that
uses, as an emission source, another semiconductor light emitting
device of a different emission wavelength from the first light
source; a wavelength converting member that is excited for light
emission by light emitted from at least one of the first and second
light sources; and a light quantity changing unit that changes a
light quantity ratio between the light emitted from the first light
source and the light emitted from the second light source.
2. The lighting device for an endoscope according to claim 1,
wherein the semiconductor light emitting device of at least one of
the first light source and the second light source has an emission
wavelength of 400 nm to 470 nm.
3. The lighting device for an endoscope according to claim 1,
wherein the wavelength converting member comprises a phosphor for
generating white light by using light emitted from the wavelength
converting member by excitation light and the light emitted from at
least one of the first and second light sources.
4. The lighting device for an endoscope according to claim 1,
further comprising: at least one third light source that uses, as
an emission source, a semiconductor light emitting device of a
different emission wavelength from the first and second light
sources, with the emission wavelengths being different among the
light sources.
5. The lighting device for an endoscope according to claim 1,
further comprising: an optical coupling unit that is disposed on an
optical path extending from the first light source to the
wavelength converting member and that guides the light emitted from
at least the second light source together with the light emitted
from the first light source to the wavelength converting
member.
6. The lighting device for an endoscope according to claim 2,
wherein the emission wavelength of one of the first light source
and the second light source is set to a wavelength on a shorter
wavelength side and the emission wavelength of the other is set to
a wavelength on a longer wavelength side of a maximum peak
wavelength of an absorption wavelength band of hemoglobin
sandwiched therebetween.
7. The lighting device for an endoscope according to claim 1,
wherein the light quantity ratio changing means changes quantities
of the light emitted from the light sources independently.
8. The lighting device for an endoscope according to claim 1,
further comprising: an input unit that is input light quantity
ratio information specifying a desired light quantity ratio,
wherein the light quantity ratio changing unit respectively
determines the quantities of the light emitted from the light
sources for attaining the desired light quantity ratio based on the
light quantity ratio information input to the input unit.
9. The lighting device for an endoscope according to claim 8,
further comprising: a memory unit that stores a light quantity
ratio table listing key information in relation to a plurality of
light quantity ratios, wherein the light quantity ratio information
includes the key information, and the light quantity ratio changing
unit determines the desired light quantity ratio by referring to
the light quantity ratio table based on the key information
included in the light quantity ratio information input through the
input unit.
10. The lighting device for an endoscope according to claim 9,
wherein the key information comprises identification information of
an operator of an endoscope device.
11. The lighting device for an endoscope according to claim 9,
wherein the key information comprises individual identification
information of an endoscope device.
12. The lighting device for an endoscope according to claim 9,
wherein the input unit comprises a change-over switch for
specifying any of the plurality of light quantity ratios listed in
the light quantity ratio table.
13. An endoscope device, comprising: an illuminating unit that
emits the illumination light obtained by the lighting device for an
endoscope of claim 1 from a tip portion of an endoscope insertion
section to be inserted into a body cavity; and an imaging unit that
includes, in the endoscope insertion section, an imaging device for
capturing an image of an observation target region irradiated with
the illumination light and that outputs a picture signal for
forming an observation image.
14. The endoscope device according to claim 13, further comprising:
a light source controlling unit that allows at least the first
light source and the second light source to emit light within one
frame of the picture signal of the imaging device.
15. The endoscope device according to claim 14, wherein the light
source controlling unit allows at least the first light source and
the second light source to emit light at different timing within
one frame of the picture signal of the imaging device.
16. The endoscope device according to claim 13, further comprising:
an imaging processing unit that generates a display observation
image based on the picture signal output from the imaging device;
and a displaying unit that displays information including the
display observation image.
17. The endoscope device according to claim 16, wherein the
displaying unit simultaneously displays, in one screen: first image
information obtained under visible light including the light
emitted from the first light source and excited light emitted from
the wavelength converting member; and second image information
obtained under illumination light including the light emitted from
the second light source in addition to the visible light.
18. The endoscope device according to claim 16, wherein the
displaying unit simultaneously displays, in an overlapped manner:
first image information obtained under visible light including the
light emitted from the first light source and excited light emitted
from the wavelength converting member; and second image information
obtained under illumination light including the light emitted from
the second light source in addition to the visible light.
19. The endoscope device according to claim 13, further comprising:
a memory unit that stores information including the observation
image output from the image processing unit, wherein the memory
unit stores the observation image in relation to the light quantity
ratio.
Description
TECHNICAL FIELD
[0001] The present invention relates to a lighting device for an
endoscope and an endoscope device.
BACKGROUND ART
[0002] In a general endoscope device, light emitted from a lamp of
a light source system is guided to an endoscope tip portion by a
light guide provided inside an endoscope insertion section to be
inserted into a subject and is emitted through an illuminating
window disposed in the endoscope tip portion, and thus, an
observation site of the subject is illuminated. White light is used
for observation of general organism tissues, but in recent years,
an endoscope device capable of enhancing a state of a mucosal
tissue through irradiation with light of a wavelength of a specific
narrow band or capable of special light observation for observing
autofluorescence of a fluorescent material precedently administered
is utilized (Patent Documents 1 and 2). When such a type of
endoscope device is used, since organism tissue is irradiated with
special light, neovascular generated in a mucosal layer or a
submucosal layer may be observed, and hence, a microstructure of a
mucosal surface not obtained in a general observation image may be
described.
[0003] In Patent Documents 1 and 2 mentioned above, merely a
specific wavelength band of light emitted from a white light source
such as a xenon lamp is taken out by using a color filter so as to
be used as the special light. It is noted that a laser light source
may be used as the white light source apart from the xenon lamp,
and a light emitting apparatus for generating white light through a
combination of, for example, a blue laser light source and a
phosphor causing excitation emission by using a blue laser beam as
excitation light has been proposed (Patent Document 3).
[0004] The endoscope device of each of Patent Documents 1 and 2,
however, employs a structure in which the light emitted from the
white light source is divided on a time basis by a color filter so
as to frame-sequentially emit light of different wavelength bands
(of, for example, R, G and B). Therefore, it is necessary to
synthesize captured images of a plurality of frames (of R, G and B)
for obtaining a full-color observation image, which prevents
increase of the frame rate of an observation image. Furthermore,
since the illumination light is generated through light absorption
with the color filter, the quantity of light is unavoidably
reduced, which is a factor to increase a noise component of the
observation image. Although it is possible to increase the
sensitivity by reducing the frame rate, a resultant image is easily
blurred in this case.
[0005] On the other hand, in diagnosis with special light, tissue
information of, for example, a surface layer portion or a portion
toward a deep layer portion of organism tissue is a significant
observation target. In regard to, for example, a cancer of a
digestive organ, tumor vessels appear in a mucosal surface layer
portion at an early stage, and the tumor vessels are found to
expand, meander and increase in the density as compared with
general blood vessels appearing in the surface layer portion.
Therefore, the kind of tumor may be identified by dissecting the
characters of the vessels. In the aforementioned endoscope device
using a color filter, however, when tissue information of a surface
layer portion of organism tissue in particular, for example, is
desired to observe, it is difficult to restrict the transmission
wavelength band of the color filter to a specific narrow band, and
in addition, the illumination light of the restricted narrow band
may not be obtained in a sufficient quantity, and therefore, the
image quality of an observation image is disadvantageously
degraded.
Prior Art Documents
Patent Documents
[0006] Patent Document 1: Japanese Patent No. 3583731
[0007] Patent Document 2: Japanese Patent Publication No.
6-40174-B
[0008] Patent Document 3: Japanese Laid-Open Patent Publication No.
2006-173324-A
DISCLOSURE OF THE INVENTION
Problem to be Solved by the Invention
[0009] An object of the invention is providing a lighting device
for an endoscope and an endoscope device capable of obtaining
desired tissue information of organism tissue in a clearer state
suitable to diagnosis in observation of the organism tissue with
white light or special light.
Means for Solving the Problem
[0010] The present invention includes the following:
[0011] (1) A lighting device for an endoscope obtaining
illumination light by using light emitted from a plurality of light
sources, including: a first light source that uses a semiconductor
light emitting device as an emission source; a second light source
that uses, as an emission source, another semiconductor light
emitting device of a different emission wavelength from the first
light source; a wavelength converting member that is excited for
light emission by light emitted from at least one of the first and
second light sources; and light quantity ratio changing means that
changes a light quantity ratio between the light emitted from the
first light source and the light emitted from the second light
source.
[0012] (2) An endoscope device including an illuminating optical
system that emits illumination light from the aforementioned
lighting device for an endoscope from a tip of an endoscope
insertion section; and an imaging optical system that includes an
imaging device that receives light from an illuminated region
irradiated with the illumination light and that outputs a picture
signal.
Effects of the Invention
[0013] According to the lighting device for an endoscope and the
endoscope device of the present invention, desired tissue
information of organism tissue may be obtained in a clearer state
suitable to diagnosis in observation of the organism tissue with
white light or special light of a specific wavelength band.
BRIEF DESCRIPTION OF DRAWINGS
[0014] [FIG. 1] This is a schematic diagram of an endoscope device
using a lighting device for an endoscope used for describing an
embodiment of the invention.
[0015] [FIG. 2] This is a block diagram of the endoscope device of
FIG. 1.
[0016] [FIG. 3] This is a graph of emission spectra of a laser beam
emitted from a violet laser light source, a blue laser beam emitted
from a blue laser light source and light obtained by a phosphor
through wavelength conversion of the blue laser beam.
[0017] [FIG. 4] This is a detailed block diagram of an image
processing part.
[0018] [FIG. 5] This is an explanatory diagram schematically
illustrating blood vessels of a mucosal surface layer of organism
tissue.
[0019] [FIG. 6] This is an explanatory diagram illustrating
schematic display examples of an observation image obtained by the
endoscope device.
[0020] [FIG. 7A] This is an enlarged observation image of the
inside of a lip observed by the endoscope device with white
light.
[0021] [FIG. 7B] This is an enlarged observation image of the
inside of the lip observed by the endoscope device with a light
quantity ratio set to 50:50.
[0022] [FIG. 7C] This is an enlarged observation image of the
inside of the lip observed with a light quantity ratio set to 75:25
by the endoscope device.
[0023] [FIG. 8] This is an explanatory diagram illustrating an
example of a display screen of a display part displaying an
observation image obtained by the endoscope device.
[0024] [FIG. 9] This is an explanatory diagram illustrating another
example of the display screen of the display part displaying an
observation image obtained by the endoscope device.
[0025] [FIG. 10] This is a graph illustrating the relationship
between a current applied to a light source and the quantity of
emitted light.
[0026] [FIG. 11] This is a graph illustrating a pulse current
superimposed waveform of the applied current.
[0027] [FIG. 12] This is an explanatory diagram illustrating
various drive waveforms (a), (b) and (c) obtained under pulse
modulation control.
[0028] [FIG. 13] This is a graph illustrating an example of control
for alternately maximizing the quantities of light emitted from
light sources.
[0029] [FIG. 14] This is a graph illustrating rough relationships
between an absorption wavelength band of hemoglobin and emission
wavelengths of the light sources.
[0030] [FIG. 15] This is an explanatory diagram schematically
illustrating the states of a displayed image of the display part
obtained when an operator of an endoscope moves the endoscope
insertion section within a subject, performs observation in a
desired observation position with narrow band light and moves it to
a next observation position.
[0031] [FIG. 16] This is an explanatory diagram illustrating an
example in which a general image and a narrow band image are
arranged in their individual positions within one screen to be
simultaneously displayed.
[0032] [FIG. 17] This is an explanatory diagram illustrating an
example in which a desired range of a narrow band image is
overlapped on a general image to be simultaneously displayed.
[0033] [FIG. 18] This is an explanatory diagram of a light quantity
ratio table in which light quantity ratios for respective operators
of the endoscope are registered.
[0034] [FIG. 19] This is an explanatory diagram illustrating an
example in which preset light quantity ratios are displayed in the
display part.
[0035] [FIG. 20] This is an explanatory diagram of an operation of
a change-over switch.
[0036] [FIG. 21] This is an explanatory diagram illustrating a
table of color conversion factors listed correspondingly to the
light quantity ratios.
[0037] [FIG. 22] This is a graph illustrating absorption spectra of
hemoglobin Hb with a low oxygen concentration and oxygenated
hemoglobin HbO.sub.2 saturated with oxygen.
[0038] [FIG. 23] This is a block diagram illustrating an
exemplified structure of a light source system including a
plurality of laser light sources and an endoscope.
[0039] [FIG. 24] This is a block diagram illustrating an
exemplified structure of a light source system including an
integrated optical path and an endoscope.
[0040] [FIG. 25] This is a graph illustrating emission spectra of
the light source system and a phosphor of FIG. 24.
MODE FOR CARRYING OUT THE INVENTION
[0041] Now, a preferred embodiment of the invention will be
described in detail with reference to the accompanying
drawings.
[0042] FIG. 1 is a schematic diagram of an endoscope device using a
lighting device for an endoscope used for describing an embodiment
of the invention, and FIG. 2 is a block diagram of the endoscope
device of FIG. 1.
[0043] The endoscope device 100 of FIG. 1 includes an endoscope 11
and a control unit 13 connected to the endoscope 11. The control
unit 13 is connected to a display part 15 for displaying image
information and the like and an input part 17 for accepting an
input operation. The endoscope 11 is an electronic endoscope
including an illuminating optical system for emitting illumination
light from a tip of an endoscope insertion section 19 and an
imaging optical system including an imaging device for capturing an
image of an observation target region.
[0044] The endoscope 11 includes the endoscope insertion section 19
to be inserted into a subject; an operation section 23 for
conducting a bending operation of the tip of the endoscope
insertion section 19 and conducting operations such as suction, air
supply, water supply and the like from the tip of the endoscope
insertion section 19; a connector 25 for removably connecting the
endoscope 11 to the control unit 13; and a universal cord section
27 for connecting the operation section 23 and the connector 25 to
each other. Although not shown in the drawings, various channels
including a clamp channel through which a tool for picking a tissue
or the like is inserted and channels for supplying air and water
are provided inside the endoscope 11.
[0045] The endoscope insertion section 19 includes a soft portion
31 with flexibility, a bending portion 33 and a tip portion
(hereinafter also referred to as the endoscope tip portion) 35. In
the endoscope tip portion 35, illuminating ports 37A and 37B
through which an observation target region is irradiated with light
and an imaging device 21 such as a CCD (charge coupled device)
image sensor or a CMOS (complementary metal-oxide semiconductor)
image sensor for obtaining image information of the observation
target region are provided. The imaging device 21 may be a primary
color type imaging device with sensitivity to R (red), G (green)
and B (blue) or a complementary color type imaging device with
sensitivity to C (cyan), M (magenta) and Y (yellow) or to C, M, Y
and G. It is noted that the imaging device 21 is provided with an
image forming member 39 such as an objective lens.
[0046] The bending portion 33 is provided between the soft portion
31 and the tip portion 35 and is bendable through, for example, a
wire operation conducted by the operation section 23 or an
operation conducted by activating an actuator. This bending portion
33 may be bent to an arbitrary direction at an arbitrary angle in
accordance with a site or the like of a subject for which the
endoscope 11 is used, so as to make the illuminating ports 37A and
37B of the endoscope tip portion 35 and an observation direction of
the imaging device 21 face toward a desired observation site.
Furthermore, although not shown in the drawing, the illuminating
ports 37A and 37B of the endoscope insertion section 19 are
provided with a cover glass and a lens.
[0047] The control unit 13 includes a light source system 41 for
generating the illumination light to be supplied to the
illuminating ports 37A and 37B of the endoscope tip portion 35; and
a processor 43 for performing image processing of picture signals
supplied from the imaging device 21, and is connected to the
display part 15 and the input part 17. The processor 43 performs
the image processing of picture signals transmitted from the
endoscope 11 on the basis of an instruction given from the
operation section 23 of the endoscope 11 or the input part 17, so
as to generate display images and to supply the generated images to
the display part 15.
[0048] Optical fibers 45A and 45B for guiding the illumination
light from the light source system 41 and a scope cable 47 for
connecting the imaging device 21 and the processor 43 to each other
are inserted through the endoscope 11. Furthermore, although not
shown in the drawings, various signal lines extending from the
operation section 23 and tubes of air supply and water supply
channels and the like are also connected to the control unit 13 and
the like through the universal cord section 27 via the connector
25. The connector 25 on the side of the endoscope 11 is removably
connected to the connector parts 26A and 26B respectively provided
on the light source system 41 and the processor 43 as illustrated
in FIG. 2.
[0049] The light source system 41 includes, as emission sources, a
blue laser light source (a first light source) 51 with a center
wavelength of 445 nm and a violet laser light source (a second
light source) 53 with a center wavelength of 405 nm as illustrated
in FIG. 2. Beams emitted from semiconductor light emitting devices
of the light sources 51 and 53 are individually controlled by
alight source control part 55, so that alight quantity ratio
between light emitted from the blue laser light source 51 and light
emitted from the violet laser light source 53 may be freely
changed.
[0050] For the blue laser light source 51 corresponding to the
first light source and the violet laser light source 53
corresponding to the second light source, a broad area type
InGaN-based laser diode may be used, or alternatively an
InGaNAs-based laser diode or a GaNAs-based laser diode may be used.
Furthermore, a luminous element such as a light emitting diode may
be used as the light source.
[0051] The laser beams emitted from the light sources 51 and 53 are
input to the optical fibers by condensing lenses (not shown) and
are propagated to the endoscope tip portion 35 (see FIG. 1) of the
endoscope 11 respectively by the optical fibers 45A and 45B through
the connector part 26A and the connector 25 (see FIG. 1) on the
side of the endoscope 11. Then, the laser beam emitted from the
blue laser light source 51 irradiates a phosphor 57 corresponding
to a wavelength converting member disposed in the endoscope tip
portion 35, and the laser beam emitted from the violet laser light
source 53 irradiates a light deflecting/diffusing member 59.
[0052] Each of the optical fibers 45A and 45B is a multimode fiber,
and for example, a thin cable with a core diameter of 105 .mu.m, a
cladding diameter of 125 .mu.m and a diameter .phi. including an
outer cover of a protection layer of 0.3 to 0.5 mm may be used.
[0053] The phosphor 57 includes a plurality of kinds of phosphors
(such as a YAG-based phosphor and a phosphor including BMA
(BaMgAl.sub.10O.sub.27) or the like) that absorb a part of the blue
laser beam emitted from the blue laser light source 51 and emit
light of green to yellow through excitation. As a result, the
excited light of green to yellow obtained from the excitation light
of the blue laser beam emitted from the blue laser light source 51
and a part of the blue laser beam not absorbed by but passing
through the phosphor 57 are combined so as to generate white
(pseudo white) illumination light. When the semiconductor light
emitting device is used as the excitation light source as in this
exemplified structure, white light with high density may be
obtained with high efficiency, and furthermore, the intensity of
the white light may be easily adjusted. In addition, change of the
white light in color temperature and chromaticity may be small.
[0054] Incidentally, as the blue laser light source 51, the
phosphor 57 and the optical fiber 45A connecting them to each
other, "Micro-White" (trade name) manufactured by Nichia
Corporation may be used.
[0055] Furthermore, the light deflecting/diffusing member 59 may be
a material capable of transmitting the laser beam emitted from the
violet laser light source 53, and for example, a resin material
with a translucent property, glass or the like is used. Moreover,
the light deflecting/diffusing member 59 may employ a structure in
which a light diffusing layer of fine irregularities or a mixture
of particles (of a filler or the like) with different refractive
indexes is provided on a surface or the like of a resin material or
glass, or a structure using a translucent material. Thus,
transmitted light outgoing from the light deflecting/diffusing
member 59 becomes illumination light of a narrow band wavelength
that attains a uniform light quantity in a prescribed irradiated
region.
[0056] Incidentally, the phosphor 57 and the light
deflecting/diffusing member 59 may prevent phenomenon such as
superimpose of noise that may be an obstacle in imaging and
occurrence of a flicker in displaying a dynamic image derived from
speckle occurring due to coherence of laser beams. Furthermore, in
consideration of a difference in the refractive index between a
fluorescent material included in the phosphor 57 and a
fixing/solidifying resin used as a filler, the phosphor 57 is
preferably made of a fluorescent material itself and a particle
diameter of the filler that little absorb but largely scatter light
of the infrared region. Thus, a scattering effect may be increased
without lowering the light intensity of light of the red region or
the infrared region, there is no need to provide optical path
changing means such as a concave lens and optical loss may be
reduced.
[0057] FIG. 3 is a graph illustrating emission spectra of a laser
beam emitted from the violet laser light source 53, a blue laser
beam emitted from the blue laser light source 51 and light obtained
from the blue laser beam through the wavelength conversion by the
phosphor 57. The violet laser beam emitted from the violet laser
light source 53 is expressed as an emission line with a center
wavelength of 405 nm (i.e., a profile A). Furthermore, the blue
laser beam emitted from the blue laser light source 51 is expressed
as an emission line with a center wavelength of 445 nm, and the
excited light obtained from the blue laser beam and emitted from
the phosphor 57 exhibits a spectral intensity distribution having
emission intensity increased in a wavelength band of approximately
450 to 700 nm (i.e., a profile B). Owing to the profile B of the
excited light and the blue laser beam, the aforementioned white
illumination light is generated.
[0058] The white light herein means not only light strictly
including all wavelength components of visible light but also light
including specific wavelength bands such as R, G and B, and
includes, in a broad sense, light including a wavelength component
from green to red, light including a wavelength component from blue
to green, and the like.
[0059] Specifically, the illumination light is generated in this
endoscope device 100 by relatively increasing/decreasing the
emission intensities of the profile A and the profile B, and hence,
illumination light having different characteristics may be obtained
in accordance with a mixing ratio between the profiles A and B.
[0060] FIG. 2 will be referred to again for giving further
description. The illumination light obtained by the combination of
the blue laser light source 51 and the phosphor 57, and the violet
laser light source 53 as described above is emitted from the tip
portion of the endoscope 11 toward an observation target region of
a subject. Then, a state of the observation target region
irradiated with the illumination light is imaged by forming an
image on the imaging device 21 by an imaging lens 61.
[0061] A picture signal output from the imaging device 21 after the
imaging is converted into a digital signal by an A/D converter 63
and input to an image processing part 65 of the processor 43. In
the image processing part 65, the input picture signal is converted
into image data and subjected to appropriate image processing, so
as to generate desired output image information. Then, the thus
obtained image information is displayed through a control part 67
in the display part 15 as an endoscope observation image.
Furthermore, the image information is recorded in a recording
device 69 including a memory or a storage device if necessary.
[0062] The recording device 69 may be contained in the processor 43
or connected to the processor 43 through a network. Information on
an endoscope observation image to be recorded in the recording
device 69 is recorded in combination with information on a light
quantity ratio employed in the imaging. Therefore, the recorded
endoscope observation image may be accurately interpreted after the
endoscopic observation, and furthermore, the image may be subjected
to appropriate image processing such as standardization in
accordance with the light quantity ratio, and thus, an application
range of the endoscope observation image may be expanded. In
particular, when spectral reflectance is estimated with the number
of bands (R, G and B) increased in a pseudo manner on the basis of
information on a plurality of images obtained with spectrally
different light quantity ratios, color difference may be more
finely separated.
[0063] FIG. 4 is a detailed block diagram of the image processing
part. A picture signal input from the imaging device 21 to the
image processing part 65 is first input to a brightness calculating
section 65a. The brightness calculating section 65a obtains
brightness information of the picture signal such as the maximum
brightness, the minimum brightness and screen average brightness,
so as to normalize the brightness. Then, in the case where the
brightness of the picture signal is too low or too high, it outputs
a correction signal to the light source control part 55 for
increasing/decreasing the quantities of light emitted from the
light sources 51 and 53 so that the picture signal may attain a
desired brightness level.
[0064] Next, a color matching section 65b adjusts the normalized
image data so that the image may attain desired color tone. For
example, when the picture signal includes signals of the colors R,
G and B, it adjusts intensity balance among the signals of the
colors R, G and B. In the above-described light source system 41,
the quantities of light emitted from the blue laser light source 51
and the violet laser light source 53 are respectively controlled by
the light source control part 55, so that the light quantity ratio
between the light emitted from the blue laser light source 51 and
the light emitted from the violet laser light source 53 may be
arbitrarily changed. Therefore, chromaticness and total illuminance
of the illumination light are varied sometimes in accordance with
the set light quantity ratio, and hence, the brightness calculating
section 65a and the color matching section 65b correct a picture
signal in accordance with the set light quantity ratio so as to
retain the color tone and the brightness of an observation image at
a prescribed constant level.
[0065] Then, an image calculating section 65c performs image
calculation precedently determined or requested, and supplies a
result of the image calculation to a display image generating
section 65d, where output image information is created and output
to the control part 67.
[0066] Next, application of the aforementioned endoscope device 100
to observation of a blood vessel image of organism tissue surface
layer will be described.
[0067] FIG. 5 is an explanatory diagram schematically illustrating
blood vessels of a mucosal surface layer of organism tissue. In the
mucosal surface layer of the organism tissue, blood capillaries B2
such as dendritic vasoganglions are formed from a blood vessel B1
of a mucosal deep layer up to the mucosal surface layer, and it is
reported that a lesion of the organism tissue appears in a
microstructure of the blood capillaries B2 or the like. Therefore,
in recent years, an image of blood capillaries of a mucosal surface
layer enhanced by using light of a specific narrow band wavelength
is observed by an endoscope device, so as to aim at early detection
of a minute lesion or diagnosis of a lesion range.
[0068] When the illumination light enters the organism tissue, the
incident light is propagated diffusely in the organism tissue, and
since the absorption/diffusion characteristic of the organism
tissue has wavelength dependency, light of a shorter wavelength
tends to have a strong diffusing characteristic. In other words,
the extent of spread of the light depends upon the wavelength of
the illumination light. On the other hand, blood flowing through a
blood vessel has a peak absorption and attains high contrast at a
wavelength in the vicinity of 400 to 420 nm. For example, when the
illumination light is in a wavelength band .lamda.a in the vicinity
of a wavelength 400 nm, blood vessel information of blood
capillaries of a mucosal surface layer may be obtained, and when it
is in a wavelength band .lamda.b in the vicinity of a wavelength
500 nm, blood vessel information including blood vessels present in
a deeper layer may be obtained. Therefore, for the observation of
blood vessels of a surface layer of organism tissue, alight source
with a center wavelength of 360 to 800 nm, preferably 365 to 515 nm
and more preferably 400 to 470 nm is used.
[0069] Accordingly, as illustrated in FIG. 6 as schematic display
examples of an observation image obtained by an endoscope device,
in an observation image obtained when the illumination light is
white light, an image of blood vessels of a comparatively deep
mucosal layer is obtained, and on the other hand, minute blood
capillaries present in a mucosal surface layer are blurred. On the
contrary, in an observation image obtained when the illumination
light is narrow band light of a short wavelength alone, minute
blood capillaries of a mucosal surface layer may be clearly
seen.
[0070] In this exemplified structure, the light quantity ratio
between the light emitted from the blue laser light source 51 with
the center wavelength of 445 nm and the light emitted from the
violet laser light source 53 with the center wavelength of 405 nm
is freely changed by the light source control part 55 (see FIG. 2)
of the endoscope device 100. The change of the light quantity ratio
is conducted by operating, for example, a switch 89 provided on the
operation section 23 of the endoscope 11 of FIG. 1, and thus, the
image may be enhanced so that blood capillaries of a mucosal
surface layer may be more easily observed. Specifically, when a
blue laser beam component of the blue laser light source 51
occupies a larger ratio, the illumination light includes a white
light component derived from the blue laser beam and the excited
light generated by the phosphor 57 in a larger ratio, and hence, an
observation image as the white light observation image of FIG. 6
may be obtained. However, since the blue laser beam, that is,
narrow band light, is mixedly included in the illumination light,
blood capillaries of the surface layer are enhanced in the
observation image.
[0071] Alternatively, when a violet laser beam component of the
violet laser light source 53 occupies a larger ratio, an
observation image as the narrow band light observation image of
FIG. 6 is obtained. When the light quantity ratio between the light
emitted from the blue laser light source 51 and the light emitted
from the violet laser light source 53 is increased/decreased,
namely, when the ratio of the violet laser beam component in the
whole illumination light components is increased/decreased, the
minute blood capillaries of the mucosal surface layer may be
continuously enhanced for the observation.
[0072] Accordingly, as the violet laser beam component occupies a
larger ratio, the minute blood capillaries included in a thin depth
region of the mucosal surface layer are clearly shown in the
observation image, and as the ratio of the violet laser beam
component is smaller, information of blood vessels included in a
wide depth region spread from the mucosal surface layer to the deep
layer is shown. Therefore, a blood vessel distribution along a
depth direction from the mucosal surface layer may be displayed in
a pseudo manner, and blood vessel information along the depth
direction of an observation site may be extracted as continuous
information corresponding to respective depth ranges. In
particular, in this exemplified structure, the blood vessel
information obtained by using the blue laser beam and the blood
vessel information of the surface layer obtained by using the
violet laser beam are both extracted, and since these information
may be displayed as images to be compared with each other, the
blood vessel information including blood vessels of a shallower
surface layer portion that may not be observed by using the blue
laser beam may be observed with increased visibility.
[0073] In the tip portion 35 (see FIG. 1) of the electronic
endoscope where the imaging device 21 is disposed, a heat release
value is increased in accordance with recent increase of pixels,
increase of a frame rate and increase of power consumption, and
hence, light that may be emitted from the tip portion 35 is also
restricted. Under these circumstances, when the light quantity
ratio between the light sources is changed so as to increase
necessary light emission while suppressing the total light quantity
of the illumination light, a problem, for example, that image
processing alone is employed resulting in an image unavoidably
having large noise may be overcome.
[0074] At this point, FIGS. 7A, 7B and 7C illustrate enlarged
images of the inside of a lip observed by using the endoscope
device 100 with the same light quantity under similar conditions of
image processing. These drawings illustrate an observation image
obtained with the white light illumination light including the blue
laser beam of the center wavelength of 445 nm and the excited light
of the phosphor (FIG. 7A), an observation image obtained when the
light quantity ratio between the violet laser beam of the center
wavelength of 405 nm and the blue laser beam of the center
wavelength of 445 nm is set to 50:50 (FIG. 7B), and an observation
image obtained when the light quantity ratio between the violet
laser beam of the center wavelength of 405 nm and the center
wavelength of 445 nm is set to 75:25 (FIG. 7C). It is noted that
the excited light caused through the excitation of the blue laser
beam of the center wavelength of 445 nm and emitted from the
phosphor is included in the illumination light also in FIGS. 7B and
7C.
[0075] In the observation images of FIGS. 7A, 7B and 7C, the depth
of the observation from the surface layer is smaller in the order
of 7A, 7B and 7C in accordance with the wavelength of the
illumination light, and the amount of minute blood capillaries
shown is increased in this order. In other words, as the ratio of
the violet laser beam in the illumination light is increased, the
blood capillaries of the surface layer are more enhanced in the
image, and hence, the blood capillaries of the mucosal surface
layer and a mucosal fine pattern may be more clearly observed with
increased contrast. Furthermore, since the light quantity ratio
between the blue laser beam and the violet laser beam may be freely
changed without stages, it is easy to presume a stereo structure of
blood vessels in the mucosal surface layer or to selectively and
clearly show a desired observation target on the basis of change in
the observation image caused in continuously changing the light
quantity ratio.
[0076] With regard to the violet light and the blue light of the
wavelength bands close to each other, it is difficult to realize
the increase/decrease of the light quantity of the violet region
alone distinguishably from the light of the blue region by using a
conventional halogen or xenon lamp and wavelength limiting means
such as a color filter. When an emission spectrum is narrowed in
the wavelength band by using the wavelength limiting means disposed
on an optical path, the original light quantity of the halogen or
xenon lamp is small, and in addition, the quantity of light of the
violet region is further insufficient. Moreover, when the
half-width of the emission spectrum is to be increased for
increasing the quantity of the light of the violet region, the
illumination light may not be narrowed in the wavelength band, and
a desired blood vessel is insufficiently enhanced in a resultant
image.
[0077] When the light quantity of the illumination light is
insufficient, the insufficient light quantity may be dealt with
generally by increasing the sensitivity of an image sensor or
decreasing a frame rate, and however, when the sensitivity of the
image sensor is increased in capturing an image, a noise component
of the captured image is disadvantageously increased.
Alternatively, when the sensitivity is increased by decreasing the
frame rate, blurring is increased and an observation image becomes
obscure on the contrary. Since the laser beams are used as the
light sources in this exemplified structure, the illumination light
with high intensity is always stably obtained, an observation image
may be bright, and in addition, a high image quality with low noise
may be obtained. Furthermore, even when an image of a distant site
is captured, necessary sufficient luminous intensity may be
attained.
[0078] The aforementioned light quantity ratio is changed by the
light source control part 55 of FIG. 2 through control of the light
sources 51 and 53, and next, a method for changing the light
quantity ratio by an operator while keeping an observation image in
sight will be described with reference to FIGS. 8 and 9.
[0079] FIG. 8 illustrates an example of a display screen 71 of the
display part 15 for displaying an observation image obtained by the
endoscope device 100. The display screen 71 is provided with an
endoscope image area 73 where an observation image obtained by the
endoscope device is displayed, a general image switching button 75
for allowing an observation image obtained with the general white
light illumination to be displayed in the endoscope image area 73,
and a narrow band light image switching button 77 for allowing an
observation image obtained with narrow band illumination light of
the violet laser beam to be displayed, and is further provided with
an adjusting bar 79 and a knob 81 used for adjusting the light
quantity ratio. On the basis of an instruction given through the
input part 17 of a mouse or a keyboard, the knob 81 is slidingly
moved inside the adjusting bar 79, so as to adjust the light
quantity ratio for attaining a desired observation image.
[0080] The control part 67 determines the light quantity ratio in
accordance with the position of the knob 81 in the adjusting bar
79, and drives the light sources 51 and 53 so as to attain the
quantities of light emitted from the light sources 51 and 53
corresponding to the determined light quantity ratio. At this
point, a relationship between the light quantity ratio and the
quantities of light emitted from the light sources 51 and 53 is
stored in a memory part 83 (see FIG. 2) as a light quantity ratio
correspondence table, and the control part 67 obtains the
quantities of light to he emitted from the light sources 51 and 53
by referring to the light quantity ratio correspondence table of
the memory part 83.
[0081] In setting a desired light quantity ratio by
increasing/decreasing the quantities of the light emitted from the
light sources 51 and 53 (see FIG. 1) as described above, the
control part 67 determines the quantities of the light to be
emitted from the light sources 51 and 53 by referring to the light
quantity ratio correspondence table precedently stored on the basis
of the light quantity ratio set in the display screen 71. In this
manner, a desired light quantity ratio may be obtained through a
simple operation without an operator of the endoscope directly
setting the quantities of the light to be emitted from the light
sources 51 and 53.
[0082] Alternatively, as illustrated in FIG. 9, the light quantity
ratio may be set instead by using a setting portion 85 for making
various adjustments of intensity balance among the respective
colors R, G and B of a picture signal, the brightness and the
contrast, or by using the setting portion 85 in combination with
the adjustment conducted by using the knob 81 for changing the
light quantity ratio. In this manner, a desired observation target
may be arbitrarily enhanced, for example, expressed in pseudo
colors in an observation image, and thus, the degree of freedom in
changing a displayed image may be increased, so as to obtain an
image more suitable to diagnosis.
[0083] Next, a method for driving the light sources 51 and 53 by
the light source control part 55 will be described.
[0084] The light source control part 55 of FIG. 2 controls the
quantities of the light to be emitted from the light sources 51 and
53 on the basis of an instruction given through the input part 17.
In each of the light sources 51 and 53, there is a relationship R1
between the applied current and the light quantity as illustrated
in FIG. 10, and a desired light quantity may be attained by
controlling the current applied to each of the light sources 51 and
53. In order to obtain a light quantity La, for example, the
applied current is not to 1b for securing a light quantity Lb on
the basis of the relationship R1, and a difference .DELTA.L between
the light quantity Lb and the light quantity La corresponding to a
fine adjustment margin is obtained by superimposing, on the applied
current, a pulse-modulated pulse current.
[0085] For example, as understood from a pulse current superimposed
waveform illustrated in FIG. 11, the light quantity La is obtained
by a pulse current resulting from biasing the applied current Ib.
Through such bias current control and pulse modulation control, a
dynamic range of a settable light quantity may be widely
secured.
[0086] For the pulse modulation control employed in this case, any
of various drive waveforms may be used. For example, when a pulse
waveform repeatedly turned on/off in synchronization with light
storage time for one frame of an image of the imaging device as
illustrated in FIG. 12(a) is used, it is minimally affected by a
dark current of the CCD or CMOS image sensor, and hence, the
fineness of a resultant image may be increased. Alternatively, when
a pulse waveform with a cycle sufficiently faster than the light
storage time as illustrated in FIG. 12(b) is used, the occurrence
of flicker related to image display may be reduced, and in
addition, image noise derived from speckle of the laser may be
reduced. Alternatively, when a mixed type pulse waveform
corresponding to a mixture of the pulse waveforms of FIGS. 12(a)
and 12(b), specifically in which the fast cycle pulse waveform of
FIG. 12(b) is employed in an on-period of the pulse waveform of
FIG. 12(a), is used, the aforementioned effects other than the
reduction of flicker may be attained.
[0087] Furthermore, when the light sources 51 and 53 are controlled
to alternately turn on for alternately attaining the maximum light
quantity as illustrated in FIG. 13, the maximum drive power of the
light source system 41 for both the light sources 51 and 53 may be
suppressed, and a burden on an organism, that is, a subject, may be
reduced. Furthermore, captured images obtained with the
illumination light of the light sources 51 and 53 may be
individually obtained, and in this case, the captured images may be
subjected to an inter-picture operation, and thus, the degree of
freedom in the image processing may be increased.
[0088] FIG. 14 illustrates a rough relationship between absorption
wavelength band of hemoglobin and the emission wavelengths of the
light sources 51 and 53.
[0089] Hemoglobin included in blood has an absorption peak at a
wavelength in the vicinity of 400 to 420 nm as described above, and
hence, beams emitted from the light sources 51 and 53 and having
emission wavelengths included in or in the vicinity of the
absorption wavelength band of hemoglobin may capture blood vessel
information with high contrast. Furthermore, since the emission
wavelengths of the light sources 51 and 53 are set to have
substantially the same absorption with the absorption wavelength
band of hemoglobin sandwiched therebetween, intensity of the blood
vessel information is never affected by the light quantity ratio
between the light sources 51 and 53. In other words, even when the
light quantity ratio between the light sources 51 and 53 is
changed, the sensitivity in detecting a blood vessel image itself
may be kept constant.
[0090] When light not having the maximum peak wavelength of the
absorption wavelength band of hemoglobin and having appropriate
absorption in base regions of the absorption wavelength band is
used as the illumination light, even if organism tissue bleeds in
an observation region, an observation image may be prevented from
darkening by the influence of absorption by the blood having oozed
out to the tissue surface layer.
[0091] Observation images obtained by the illumination with the
narrow band light of the violet laser beam and by the illumination
with the white light described so far may be instantly switched
with respect to every frame. FIG. 15 schematically illustrates
states of displayed images of the display part 15 (see FIGS. 1 and
2) obtained when an operator of the endoscope moves the endoscope
insertion section in a subject, performs the observation with the
narrow band light in a desired observation position and moves the
endoscope insertion section to a next observation position.
[0092] The switching from a general display image obtained through
the white light observation to a display image obtained through the
narrow band light observation and the reverse switching may be
conducted with respect to each frame of a captured image (a
full-color age of R, G and B colors) of the imaging device 21.
Therefore, even when the observation is performed while moving the
endoscope insertion section, images free from color drift may be
displayed on a real-time basis, and hence, the operator can be
prevented from feeling uncomfortable. In other words, good
observation images that may definitely follow quick movement of the
endoscope are provided, resulting in improving the operability of
the endoscope device.
[0093] Furthermore, as a display pattern for observation images in
the display part 15, a general image obtained through the white
light observation and a narrow band light image obtained through
the narrow band light observation may be freely arranged. For
example, when a general image and a narrow band light image are
respectively arranged in individual areas in one screen to be
simultaneously displayed as illustrated in FIG. 16, the general
image and the narrow band light image in which specific information
is enhanced may be easily compared with each other in the
observation. In this case, image capture with the blue laser light
source 51 turned on for a general image obtained with the white
light and image capture for a next frame with the blue laser light
source 51 and the violet laser light source 53 simultaneously
turned on for a narrow band light image are repeated, and the thus
obtained general images and narrow band light images are
respectively displayed in their individual display areas.
[0094] Alternatively, FIG. 17 illustrates a display screen in which
a desired range of a narrow band light image is overlapped on a
part of a general image for simultaneous display, namely, a display
screen having what is called a PinP (picture in picture) function.
A display range of the narrow band light image may be set to an
arbitrary position and in an arbitrary size in the general image in
accordance with an instruction given through the input part 17 (see
FIGS. 1 and 2). In the display range of the narrow band light
image, a part of the narrow band light image of a subject in the
same position as the corresponding part of the general image is
displayed. In this manner, comparative observation of the images of
the same position may be further easily conducted. Incidentally,
the aforementioned display patterns are merely exemplarily
described, a display form in which a general image is fit in a
narrow band light image may be employed, and it goes without saying
that any other possible combinations may be employed for the
display.
[0095] Next, the setting of the light quantity ratio between the
blue laser beam and the violet laser beam will be described.
[0096] As described above, the light quantity ratio between the
light emitted from the blue laser light source 51 and the light
emitted from the violet laser light source 53 of FIG. 2 may be
arbitrarily set by the light source control part 55 in accordance
with an instruction given trough the input part 17. Herein,
description will be made on a case where plural kinds of light
quantity ratios are precedently registered so as to specify one of
the light quantity ratios by using the input part 17.
[0097] In the endoscope observation of images of, for example,
blood vessels, operators of the endoscope may be different in their
preference in the light quantity ratio between the blue laser beam
and the violet laser beam. For example, an operator A may prefer an
observation image obtained with the light quantity ratio between
the violet laser beam .lamda.a and the blue laser beam .lamda.b set
to 60:40 while an operator B prefers one obtained with the light
quantity ratio set to 75:25, and thus, there may be a difference in
the preference. In this case, as illustrated in FIG. 18, light
quantity ratio information in which a name of an operator, that is,
key information, is in relation to a light quantity ratio preferred
by the operator, is precedently registered in the memory part 83
(see FIG. 2) or the like as a light quantity ratio table. Then,
when information corresponding to a name of an operator is input
through the input part 17, the control part 67 automatically sets a
desired light quantity ratio by referring to the light quantity
ratio table stored in the memory part 83. In this manner, a light
quantity ratio may be set in accordance with the preference of an
operator of the endoscope.
[0098] Furthermore, since optical characteristics may be sometimes
different among individual endoscopes, individual identification
information for identifying each of the individual endoscopes may
be used as the key information instead of a name of an operator
used as the key information above. In this case, a number, a model
name or the like given to each of the endoscopes is used and
information on a corresponding light quantity ratio is precedently
registered as the light quantity ratio table. In this manner, an
optimum light quantity ratio may be set in accordance with the type
or the characteristics of each of the individual endoscopes.
[0099] Moreover, arbitrary plural kinds of light quantity ratios
may be preset so as to be freely selected through a simple
operation performed by an operator. For example, as illustrated as
a display example of the display part 15 in FIG. 19, plural kinds
of preset light quantity ratios are displayed as "selection
buttons" 87 of GUI (graphical user interface), which may be freely
selected by an operator or an assistant by operating the input part
17 while seeing the display part 15 (see FIGS. 1 and 2).
Furthermore, when the display part 15 is a touch panel, a switching
operation may be more intuitively and quickly performed by directly
touching one of the selection buttons 87 in the display part 15
steadily gazed by the operator during the observation. In addition,
the operator may compare observation images changing in accordance
with the change of the light quantity ratio without taking his/her
eyes off, and hence, subtle change of the images may be more
definitely recognized.
[0100] Furthermore, the switching of the light quantity ratio may
be conducted not only by using the display pattern on the display
part 15 but also by operating the switch 89 provided, as a
change-over switch, on the operation section 23 of the endoscope 11
of FIG. 1. When the switch 89 is provided on the operation section
23, the light quantity ratio may be rapidly and easily changed
without the operator releasing his/her grip on the endoscope 11,
resulting in improving the operability of the endoscope.
[0101] As the switch 89, any of various switches such as a toggle
switch, a push switch, a slide switch and a rotary switch may be
used, and as illustrated in FIG. 20, precedently preset different
light quantity ratios are successively set every time the switch is
pushed once or in accordance with a contact position of a
multi-contact switch. Thus, it is possible to successively select
observation light modes with plural kinds of light quantity ratios,
such as the general light observation performed with the white
light obtained by the blue laser light source 51 and the phosphor
57 of FIG. 2, narrow band light observations A, B, C, etc. in which
the narrow band light emitted from the violet laser light source 53
is superimposed on the white light at prescribed ratios, and narrow
band light observation performed with the narrow band light
alone.
[0102] When the switching operation is performed through the
repetition of a pushing operation, there is no need to visually
recognize the switch 89 but the switching operation may be
performed while gazing at the display part 15. Therefore, the
illumination light suitable to diagnosis may be easily switched.
Incidentally, the switch 89 for changing the light quantity ratio
is not limited to a switch for changing the preset light quantity
ratios but may be a volume switch or a slide switch for
continuously changing the light quantity ratio. In this case, the
light quantity ratio may be easily adjusted to be optimum in
accordance with an observation target. Furthermore, when the light
quantity ratio is continuously changed by the switching operation,
continuous change of an observation image may be observed, and
hence, a vascular structure may be more accurately grasped.
[0103] Next, correction of color change of an observation image
caused by changing the light quantity ratio will be described.
[0104] The image processing part 65 of FIG. 4 receives picture
signals R, G and B as inputs, and the picture signals R, G and B
are normalized in the brightness by the brightness calculating
section 65a, so as to be converted into image data Rnorm, Gnorm and
Bnorm. These normalized image data Rnorm, Gnorm and Bnorm is
subjected to correction to color tone according to the light
quantity ratio by the color matching section 65b. Specifically, the
color matching section 65b obtains image data Radj, Gadj and Badj
resulting from the color tone correction through calculation in
accordance with the following equation (1):
( R adj G adj B adj ) = ( k R k G k S ) ( R norm G norm B norm )
Equation ( 1 ) ##EQU00001##
[0105] In this equation, k.sub.R, k.sub.G and k.sub.B respectively
indicate color conversion factors of the respective colors and are
determined in accordance with a light quantity ratio set in
capturing the image. FIG. 21 illustrates a color conversion factor
table in which the color conversion factors of the respective
colors are listed correspondingly to light quantity ratios. The
color conversion factors k.sub.R, k.sub.G and k.sub.B are
respectively set to R00 to R100, G00 to G100 and B00 to B100
correspondingly to the respective light quantity ratios, and are
stored in the memory part 83 (see FIG. 2). When the color
conversion factors corresponding to a light quantity ratio employed
in capturing an image are substituted in Equation (1), image data
Radj, Gadj and Badj resulting from the color tone correction is
obtained.
[0106] The color conversion factors may be expressed not only as
the table of FIG. 21 but also as an equation, or alternatively,
with merely representative points digitalized, other points may be
calculated through an interpolation operation. In this case, the
amount of information stored in the memory part 83 may be
reduced.
[0107] According to the endoscope device 100 described so far,
since the violet laser beam (and the blue laser beam), namely, the
illumination light of a shorter wavelength band suitable to the
observation of blood vessels in particular, is used, minute blood
vessels of organism tissue surface layer may be enhanced in an
image to be observed, and hence, the microstructure of the blood
vessels may be easily observed. Furthermore, since the light
quantity ratio between the violet laser beam and the blue laser
beam (white light) may be continuously changed, a vascular
structure changing along the depth direction from the organism
tissue surface layer may be easily observed, and hence, the
vascular structure in a shallower surface layer portion of the
organism tissue may be clearly grasped. Therefore, in the
observation of the organism tissue with the white light or special
light, desired tissue information on the organism tissue may be
obtained in a clearer state suitable to diagnosis, and thus, the
endoscopic diagnosis may be smoothly performed.
[0108] Furthermore, when the endoscope device 100 employs a
structure of what is called a magnifying endoscope including an
imaging optical system capable of enlarging an observation target
region for observation, separation between minute blood vessels of
organism tissue surface layer and a mucosal fine pattern may be
increased, and the endoscopic diagnosis may be performed at a
higher level. Specifically, occurrence of unusual change such as a
difference in the diameter or the shape among microvessels, and
expansion and meandering thereof, and unusual change such as
disappearance or abnormal size reduction of a mucosal fine pattern
may be found, and hence, useful information for, for example,
diagnosing the type of adenocarcinoma may be provided.
[0109] Next, an alternative structure of the endoscope device will
be described.
[0110] First, an endoscope device that obtains an oxygen
concentration distribution in blood in an observation image by
utilizing a difference in the absorption characteristic between
hemoglobin and oxygenated hemoglobin will be described.
[0111] FIG. 22 illustrates absorption spectra, at a wavelength of
450 nm to 700 nm, of hemoglobin Hb with a low oxygen concentration
and oxygenated hemoglobin HbO.sub.2 saturated with oxygen. As the
illumination light for the observation, a wavelength .lamda.1
corresponding to an isosbestic point where hemoglobin Hb and
oxygenated hemoglobin HbO2 have the same absorption and a
wavelength .lamda.2 where they have different absorption are
selected, and brightness Ab1 of an observation image obtained with
the illumination light of the wavelength .lamda.1 and brightness
Ab2 of an observation image obtained with the illumination light of
the wavelength .lamda.2 are obtained.
[0112] A ratio between the brightness Ab1 and Ab2 of these images
is used as an index corresponding to an oxygen concentration in
blood, and change in the metabolism state of organism tissue may be
monitored by using this index. It is said in general that the
oxygen concentration is low in a cancer region, and the oxygen
concentration is useful information for the endoscopic
diagnosis.
[0113] As a structure of an endoscope device for obtaining the
aforementioned oxygen concentration distribution, an endoscope
device 200 additionally includes a plurality of light sources in a
light source system 41 as illustrated as an exemplary structure of
the light source system 41 and an endoscope 11 in FIG. 23. In this
case, a blue-green laser beam emitted from a blue-green laser light
source 91 with a center wavelength of 515 nm is used as the
illumination light corresponding to the isosbestic point, for
example, and a red laser beam emitted from a red laser light source
93 with a center wavelength of 630 nm is used as the illumination
light corresponding to the wavelength where the absorption is
different. Needless to say, in the case where the measurement of
the oxygen concentration distribution is a main object, a violet
laser light source 53 may be omitted. It is noted that like
reference numerals are used in this drawing to refer to like
elements used in FIG. 2 so as to omit the description.
[0114] Incidentally, optical fibers 45A, 45B, 45C and 45D used in
the aforementioned structure are preferably selected to be optimum
respectively for wavelengths to be employed. A core of an optical
fiber has wavelength dependency in which transmission loss is
varied in accordance with the concentration of hydroxyl groups
(OH.sup.-), and an absorption ratio attained at a specified
wavelength of the infrared region is different from one attained at
a wavelength of the visible range. Therefore, when the wavelength
of a light source is 650 nm or less, an optical fiber using a core
with a high hydroxyl concentration is used, and when the wavelength
exceeds 650 nm, an optical fiber using a core with a low hydroxyl
concentration is used.
[0115] In order to obtain the oxygen concentration distribution, an
image of an observation target region is captured by using the
blue-green laser beam emitted from the blue-green laser light
source 91 as the illumination light, and then, an image of the
observation target region is captured by using the red laser beam
emitted from the red laser light source 93 as the illumination
light. In capturing the images, the quantities of light emitted
from the light sources 91 and 93 are respectively adjusted so as to
make constant an average brightness value of observation image
data. Thereafter, on the basis of brightness Ab1 and Ab2 of the
thus obtained observation images, an oxygen concentration index
Oindx is obtained with respect to each pixel in accordance with the
following Equation (2):
Oindx=k(Ab2/Ab1) Equation (2)
wherein k is a coefficient.
[0116] In this manner, an image of a distribution of the oxygen
concentration index Oindx is obtained, and a distribution state of
the oxygen concentration in the observation image may be
grasped.
[0117] Furthermore, the blue-green laser light source 91 and the
red laser light source 93 may be individually changed in the
quantity of light emitted therefrom by a light source control part
55 similarly to the blue laser light source 51 and the violet laser
light source 53, and the light quantity ratio between the light
emitted therefrom may be adjusted in accordance with an observation
target or the content of manipulation. Furthermore, each of the
laser light sources 91 and 93 may be allowed to emit light in every
frame of an imaging signal so as to appropriately adjust the light
quantity ratio therebetween. The blue-green laser beam is suitably
used for observation of microvessels or flare of organism tissue,
and the red laser beam is suitably used for observation of deep
vessels of organism tissue. Accordingly, when the light quantity
ratio between these emitted laser beams is changed, information
from regions different along the depth direction or information
from different targets may be enhanced in images to be displayed in
the same manner as described above.
[0118] Moreover, even when the light sources are allowed to
simultaneously emit light in one frame of an imaging signal, a
light component derived from the blue-green laser light source 91,
a light component derived from the red laser light source 93 or a
quantity of excited light may be separately detected from R, G and
B picture signals output from the imaging device 21.
[0119] In this manner, when the light quantity ratio of the
blue-green laser beam to the white light, the light quantity ratio
of the red laser beam to the white light or the light quantity
ratio between the blue-green laser beam and the red laser beam may
be arbitrarily and continuously changed, visibility of a desired
observation target may be improved for display. Therefore, when the
number of kinds of illumination light of an endoscope is increased
to attain multiple functions, even if there arises unexpected
necessity of observation during endoscopic diagnosis, the
observation may be promptly conducted with illumination light
appropriate to an observation target without evulsing the endoscope
from the subject. Incidentally, instead of generating the white
light from the blue laser beam and the excited light of the
phosphor, a structure using a white light source such as a halogen
lamp may be employed. In this case, the light quantity of the blue
laser beam and the light quantity of the white light may be
individually controlled, and hence, the light quantity ratio may be
more finely adjusted.
[0120] Next, an endoscope device in which an optical path from a
light source system 41 up to an endoscope 11 is constructed by one
optical fiber 45 will be described.
[0121] FIG. 24 illustrates an exemplified structure of the light
source system 41 and the endoscope 11. This endoscope device 300
includes, on an optical path where a blue laser beam emitted from a
blue laser light source 51 with a center wavelength of 445 nm is
introduced through a condensing lens not shown to an optical fiber
45A, a dichroic prism 95 corresponding to optical coupling means
for merging a violet laser beam emitted from a violet laser light
source 53 with a center wavelength of 405 nm.
[0122] A phosphor 97 disposed on a light emitting side of the
optical fiber 45A has characteristics to absorb a part of the blue
laser beam emitted from the blue laser light source 51 so as to
cause excitation emission of green to yellow light and generate
white light by combining the excited light with the blue laser beam
not absorbed by but having passed through the phosphor, and a
characteristic to minimally absorb but transmit the violet laser
beam emitted from the violet laser light source 53. Therefore, a
material that generates white light by combining excited light
caused at high efficiency by a blue laser beam with the blue laser
beam and a material that causes minimum light emission of the
phosphor by a violet laser beam are selectively used for the
phosphor 97.
[0123] There is wavelength conversion loss (Stokes loss) such as
heat generation principally caused in the wavelength conversion
attained by the phosphor 97. Therefore, it is known that the
efficiency in light emission of the phosphor is higher and the heat
generation of the phosphor may be advantageously suppressed when an
excitation wavelength with a longer emission wavelength is
selected. Therefore, in the exemplified structure, a laser beam of
a longer wavelength is used for generating the white light, so as
to improve the light emission efficiency.
[0124] FIG. 25 illustrates exemplified emission spectra of the
illumination light obtained by the light source system 41 and the
phosphor 97 of FIG. 24. As illustrated in FIG. 25, the quantity of
excitation emission of the phosphor 97 caused by the violet laser
beam is preferably one-severalth (at least one-third, preferably
one-fifth and more preferably one-tenth or less) as compared with
the quantity of light emission caused by the blue laser beam.
[0125] In this manner, since the dichroic prism 95 is used for
integrating the optical path of the blue laser beam with that of
the violet laser beam in this exemplified structure, merely one
optical fiber 45A is used for guiding the light from the light
source system 41 up to the phosphor 97, and in addition, since an
outgoing port for the illumination light may be disposed in one
position of the phosphor 97, the space efficiency may be improved
so as to make a contribution to diameter reduction of an endoscope
insertion section.
[0126] Furthermore, also when an alternative laser light source is
included apart from the blue laser light source 51 and the violet
laser light source 53, optical coupling means such as a dichroic
prism may be similarly used for integrating optical paths. Also,
with respect to the phosphor 97, a fluorescent material not excited
or minimally excited by a wavelength of the alternative laser light
source may be used.
[0127] At this point, as a specific material for the phosphor 97
used in this exemplified structure, for example, a solid
crystalline fluorescent material including lead (Pd) as an
additional element and digallium calcium tetrasulfide
(CaGa.sub.2S.sub.4) as a parent body as described in Japanese
Laid-Open Patent Publication No. 2006-2115-A, or a solid
crystalline fluorescent material including lead (Pd) and cerium
(Ce) as additional elements and digallium calcium tetrasulfide
(CaGa.sub.2S.sub.4) as a parent body may be used. When such a
fluorescent material is used, phosphor covering substantially the
whole visible range of approximately 460 nm to 660 nm may be
obtained, and thus, color rendering properties attained in the
illumination with the white light may be improved.
[0128] Alternatively, a green phosphor of LiTbW.sub.2O.sub.8 (see
"Phosphor for White Light Emitting Diode" by Tsutomu Odaki, The
Institute of Electronics, Information and Communication Engineers
Technical Report ED2005-28, CFM005-20, SDM2005-28, pp. 69-74
(2005-05), etc.), a .beta.-sialon:Eu blue phosphor (see "New Sialon
Phosphors and White LEDs" by Naoto Hirosaki, Rong-Jun Xie, Ken
Sakuma, Oyo Buturi, Vol. 74, No. 11, pp. 1449-1452 (2005) or Hajime
Yamamoto, Tokyo University of Technology, Bionics Department, Oyo
Buturi, Vo. 76, No. 3, p. 241 (2007)), a CaAlSiN.sub.3 red phosphor
and the like may be combined for use. The .beta.-sialon is crystal
obtained by solid solving aluminum and an acid in .beta.-silicon
nitride crystal and represented by a composition of
Si.sub.6-zAl.sub.2O.sub.2N.sub.8-z (wherein z is a solid solution
amount). The phosphor 97 may be a mixture of LiTbW.sub.2O.sub.8,
.beta.-sialon and CaAlSiN.sub.3, or may be made of a layered
structure of these phosphors.
[0129] Each of the phosphors exemplarily mentioned above is set to
be excited by the blue laser beam emitted from the blue laser light
source 51 but not to be excited to emit light by the violet laser
beam emitted from the other violet laser light source 53, namely,
is set to have a principal excitation wavelength band peculiar to
the phosphor not including the emission wavelength of the other
light source.
[0130] Although the white light is generated by using the blue
laser beam and the excited light emitted from the phosphor 57 or 97
in the aforementioned endoscope devices, this does not limit the
invention, but the white light may be generated by combining any of
various light sources and phosphors, for example, by a structure
using a phosphor excited to emit green light by a blue laser beam
and a phosphor excited to emit red light by a violet laser
beam.
[0131] As described so far, the followings are herein
disclosed:
[0132] (1) A lighting device for an endoscope obtaining
illumination light by using light emitted from a plurality of light
sources, including: a first light source that uses a semiconductor
light emitting device as an emission source; a second light source
that uses, as an emission source, another semiconductor light
emitting device of a different emission wavelength from the first
light source; a wavelength converting member that is excited for
light emission by light emitted from at least one of the first and
second light sources; and light quantity ratio changing means that
changes a light quantity ratio between the light emitted from the
first light source and the light emitted from the second light
source.
[0133] According to this lighting device for an endoscope, since
the light quantity ratio between the light emitted from the first
light source and the light emitted from the second light source may
be freely changed, illumination light including a light component
emitted from the first light source in a larger ratio, illumination
light including a light component emitted from the second light
source in a larger ratio and illumination light halfway
therebetween may be arbitrarily generated. Accordingly,
illumination light suitable to diagnosis may be provided in
accordance with the absorption characteristic and the scattering
characteristic of organism tissue, and hence, desired tissue
information of the organism tissue may be obtained in a clearer
state.
[0134] (2) In the lighting device for an endoscope according to
(1), the semiconductor light emitting device of at least one of the
first light source and the second light source has an emission
wavelength of 400 nm to 470 nm.
[0135] According to this lighting device for an endoscope, since
light of the semiconductor light emitting device of a wavelength of
400 nm to 470 nm is used, blood vessels of a surface layer portion
of organism tissue may be particularly enhanced for
observation.
[0136] (3) In the lighting device for an endoscope according to (1)
or (2), the wavelength converting member is a phosphor for
generating white light by using light emitted from the wavelength
converting member by excitation light and the light emitted from at
least one of the first and second light sources.
[0137] According to this lighting device for an endoscope, since
the white light is generated by using the light emitted by the
wavelength converting member with the light from the semiconductor
light emitting device used as excitation light, white light with
high intensity may be obtained at high efficiency. Furthermore,
since the semiconductor light emitting device is used as the
excitation light source, the intensity of the white light may be
easily adjusted, and in addition, change in color temperature and
chromaticity of the white light may be small.
[0138] (4) The lighting device for an endoscope according to any of
(1) to (3), further including: at least one third light source that
uses, as an emission source, a semiconductor light emitting device
of a different emission wavelength from the first and second light
sources, with the emission wavelengths being different among the
light sources.
[0139] According to this lighting device for an endoscope, since it
further includes the third light source having the different
emission wavelength, the wavelength band of the illumination light
may be increased, and the degree of freedom in selecting the
wavelength of the illumination light may be improved. Therefore,
illumination light for forming various images, such as a blood
vessel enhanced image obtained with violet light or blue light and
an oxygen concentration distribution image obtained with green
light and red light, may be obtained.
[0140] (5) The lighting device for an endoscope according to any of
(1) to (4), further including: optical coupling means that is
disposed on an optical path extending from the first light source
to the wavelength converting member and that guides the light
emitted from at least the second light source together with the
light emitted from the first light source to the wavelength
converting member.
[0141] According to this lighting device for an endoscope, a
portion extending from the optical coupling member to the
wavelength converting member may be constructed by an optical path
of one system, and hence, in fitting the lighting device for an
endoscope in an endoscope device, a simple structure with improved
space efficiency may be attained.
[0142] (6) In the lighting device for an endoscope according to any
of (2) to (5), the emission wavelength of one of the first light
source and the second light source is set to a wavelength on a
shorter wavelength side and the emission wavelength of the other is
set to a wavelength on a longer wavelength side of a maximum peak
wavelength of an absorption wavelength band of hemoglobin
sandwiched therebetween.
[0143] According to this lighting device for an endoscope, blood
vessel information may be captured with high contrast. Furthermore,
since the illumination light minimally includes a component in the
vicinity of a peak of the absorption wavelength of hemoglobin, an
observation image may be prevented from darkening through
absorption of blood oozed out to a tissue surface layer.
[0144] (7) In the lighting device for an endoscope according to any
of (1) to (6), the light quantity ratio changing means changes
quantities of the light emitted from the light sources
independently.
[0145] According to this lighting device for an endoscope, since
the light quantity of light emitted from each of the light sources
may be freely changed, the spectral characteristics of the
illumination light ultimately generated from the light of the
respective light sources may be adjusted at a high degree of
freedom.
[0146] (8) The lighting device for an endoscope according to any of
(1) to (7), further including: input means that is input light
quantity ratio information specifying a desired light quantity
ratio, the light quantity ratio changing means respectively
determining the quantities of the light emitted from the light
sources for attaining the desired light quantity ratio based on the
light quantity ratio information input to the input means.
[0147] According to this lighting device for an endoscope, the
light quantity ratio is specified in accordance with the light
quantity ratio information input through the input means, and the
quantities of the light emitted from the light sources are
determined so as to attain the light quantity ratio. In other
words, the light quantity ratio may be freely changed as
specified.
[0148] (9) The lighting device for an endoscope according to (8),
further including: memory means that stores a light quantity ratio
table listing key information in relation to a plurality of light
quantity ratios, the light quantity ratio information including the
key information, the light quantity ratio changing means
determining the desired light quantity ratio by referring to the
light quantity ratio table based on the key information included in
the light quantity ratio information input through the input
means.
[0149] According to this lighting device for an endoscope, the
desired light quantity ratio is determined by referring to the
light quantity ratio table on the basis of the key information
included in the light quantity ratio information. In other words,
since the light quantity ratios are precedently registered in
relation to respective key information in the light quantity ratio
table, the light quantity ratio corresponding to key information
may be automatically determined merely by specifying the key
information.
[0150] (10) In the lighting device for an endoscope according to
(9), the key information is identification information of an
operator of an endoscope device.
[0151] According to this lighting device for an endoscope, an
arbitrary light quantity ratio may be set with respect to each
operator of the endoscope in accordance with preference of the
operator.
[0152] (11) In the lighting device for an endoscope according to
(9), the key information is individual identification information
of an endoscope device.
[0153] According to this lighting device for an endoscope, the
light quantity ratio may be set with respect to each individual
endoscope in accordance with the type and the characteristic of the
individual endoscope.
[0154] (12) In the lighting device for an endoscope according to
any of (9) to (11), the input means is a change-over switch for
specifying any of the plurality of light quantity ratios listed in
the light quantity ratio table.
[0155] According to this lighting device for an endoscope, a
desired light quantity ratio may be arbitrarily specified out of a
plurality of kinds of light quantity ratios by operating the
change-over switch, and thus, the light quantity ratio may be
rapidly and easily switched.
[0156] (13) An endoscope device, including: illuminating means that
emits the illumination light obtained by the lighting device for an
endoscope of any one of (1) to (12) from a tip portion of an
endoscope insertion section to be inserted into a body cavity; and
imaging means that includes, in the endoscope insertion section, an
imaging device for capturing an image of an observation target
region irradiated with the illumination light and that outputs a
picture signal for forming an observation image.
[0157] According to this endoscope device, the illumination light
obtained with the light quantity ratio between the light emitted
from the first light source and the light emitted from the second
light source set to a desired light quantity ratio is used for
irradiating an observation target region and an image of the
observation target region is captured by the imaging device, and
hence, an observation image corresponding to the light quantity
ratio may be obtained. In other words, the illumination light
suitable to diagnosis may be used for illumination, and desired
tissue information of organism tissue may be obtained in a clearer
state.
[0158] (14) The endoscope device according to (13), further
including: light source controlling means that allows at least the
first light source and the second light source to emit light within
one frame of the picture signal of the imaging device.
[0159] According to this endoscope device, since an image is
captured by the imaging device with the respective light sources
allowed to emit light within one frame of the picture signal, an
observation image in which the observation target region is
irradiated with the light emitted from all of the plurality of
light sources may be obtained.
[0160] (15) In the endoscope device according to (14), the light
source controlling means allows at least the first light source and
the second light source to emit light at different timing within
one frame of the picture signal of the imaging device.
[0161] According to this endoscope device, there is no need for the
respective light sources to simultaneously emit light, and hence, a
burden on a subject and the power consumption of the device may be
suppressed.
[0162] (16) The endoscope device according to any of (13) to (15),
further including: image processing means that generates a display
observation image based on the picture signal output from the
imaging device; and displaying means that displays information
including the display observation image.
[0163] According to this endoscope device, since the displaying
means is made to display information of the picture signal supplied
from the imaging device, the observation image may be easily
checked and endoscopic diagnosis may be more smoothly
performed.
[0164] (17) In the endoscope device according to claim 16, the
displaying means simultaneously displays, in one screen: first
image information obtained under visible light including the light
emitted from the first light source and excited light emitted from
the wavelength converting member; and second image information
obtained under illumination light including the light emitted from
the second light source in addition to the visible light.
[0165] According to this endoscope device, the first image
information corresponding to an observation image obtained by using
the visible light with a large wavelength band as the illumination
light and the second image information corresponding to an
observation image obtained by using the illumination light
including narrow band light are simultaneously displayed in one
screen of the displaying means. Therefore, a general observation
image and an image in which specific information is enhanced may be
easily compared with each other for the observation.
[0166] (18) In the endoscope device according to (16) or (17), the
displaying means simultaneously displays, in an overlapped manner:
first image information obtained under visible light including the
light emitted from the first light source and excited light emitted
from the wavelength converting member; and second image information
obtained under illumination light including the light emitted from
the second light source in addition to the visible light.
[0167] According to this endoscope device, the general observation
image and the image in which the specific information is enhanced
are displayed in an overlapped manner, so as to be easily compared
with each other for the observation.
[0168] (19) The endoscope device according to any of (13) to (18),
further including: memory means that stores information including
the observation image output from the image processing means, the
memory means storing the observation image in relation to the light
quantity ratio.
[0169] According to this endoscope device, since the observation
image is recorded in relation to the light quantity ratio set in
capturing the observation image, the application range of the
observation image may be increased, so that, for example, a
recorded observation image may be subjected to image processing in
accordance with a light quantity ratio set in capturing it.
INDUSTRIAL APPLICABILITY
[0170] According to the light source device for an endoscope and
the endoscope device of this invention, desired tissue information
of organism tissue may be obtained in a clearer state suitable to
diagnosis in observation of the organism tissue by using white
light or special light of a specific wavelength band.
[0171] The present invention is not limited to the aforementioned
embodiment but modifications and variations occurring to those
skilled in the art on the basis of the description given herein and
other known techniques are intended to be covered by the appended
claims.
[0172] The present application is based on Japanese Patent
Application No. 2009-159962 filed on Jul. 6, 2009, the entire
contents of which are herein incorporated by reference.
DESCRIPTION OF REFERENCE NUMERALS
[0173] 11 endoscope
[0174] 13 control unit
[0175] 15 display part
[0176] 17 input part
[0177] 19 endoscope insertion section
[0178] 21 imaging device
[0179] 23 operation section
[0180] 35 tip portion
[0181] 37A, 37B illuminating port
[0182] 41 light source system
[0183] 43 processor
[0184] 45A, 45B, 45C, 45D optical fiber
[0185] 51 blue laser light source (first light source)
[0186] 53 blue laser light source (second light source)
[0187] 55 light source control part
[0188] 57 phosphor (wavelength converting member)
[0189] 59 light deflecting/diffusing member
[0190] 65 image processing part
[0191] 67 control part
[0192] 71 display screen
[0193] 73 endoscope image area
[0194] 75 general image switching button
[0195] 77 narrow band light switching button
[0196] 79 adjusting bar
[0197] 81 knob
[0198] 83 memory part
[0199] 85 adjusting portion
[0200] 87 selection button
[0201] 89 switch (change-over switch)
[0202] 91 blue-green laser light source
[0203] 93 red laser light source
[0204] 95 dichroic prism
[0205] 97 phosphor (wavelength converting member)
[0206] 100, 200, 300 endoscope device
[0207] A, B profile
[0208] B1, B2 blood vessel
* * * * *